"While both units posted comparable efficiency values that were, for the most part good (with the NeoPower 650 slightly edging out the NeoPower 650 Blue), and voltage regulation that only began to suffer during Test #4 it was the 650 Blue that was able to provide the cleanest DC Output Quality making it the better product in our testing by a slim margin. This coupled with the unit being significantly quieter makes the 650 Blue the unit that seems most fitting of the 650w slot in Antec's current lineup of power supplies and most fitting in enthusiast's consideration when faced with a choice between these two units."